I Have Problems With Yellowing Leaves on My Geraniums

Of the 200 Pelargonium species, of which the common garden geranium or Pelargonium hortorum, is a member, most originated in South Africa. Popular as a bedding plant, it has a compact growth habit and several diseases can cause its multicolored leaves to turn yellow.

Bacterial Blight and Verticillium Wilt

Small spots develop on the undersides of the geranium’s lower leaves, which ultimately turn yellow and die. The blight bacteria spreads rapidly through the plant’s leaf veins and a V-shape can form on the edge of the infected leaves. Verticillium wilt also causes symptoms that are very similar to these. Keeping leaf surfaces dry helps in both situations.

Pseudomonas Leaf Spot and Southern Bacterial Wilt

Water-filled spots form on the leaves and yellow rings may develop around the spots. Treatment consists of keeping the leaf surfaces dry. The lower leaves of plants affected with Southern bacterial wilt turn yellow and fall off. Avoid bringing garden-grown plants into the house, as this can transmit the disease to other plants.

Rust

Yellow spots develop on top of the leaves and they correspond with rust-colored spores underneath. The leaves eventually fall off the plant. Avoid overhead watering and keep leaves dry.